1.Theoretical Review:: This report reviewed the theoretical and empirical studies on young children's "temporally extended self"(Neisser, 1988) and its relation to self/other understanding in terms of temporal perspectives. It started by highlighting children's understanding of the connection between the past and the present self. Then it was argued that, if made a few modifications one, delayed self-recognition task should be an adequate one to assess the "attitude toward the absent objects". And reviewing research which showed that deaf children were likely to be delayed in acquiring a theory of mind, it was proposed that discourse about the absent objects and events was related to the development of self-other understanding.2.Study 1 : This study examined conversations about the past events between deaf children (age:3-5 years) and their mothers. They talked each other looking at "picture diary" which they had drawn a month before. The main findings were as follows. (1)Using the picture diary, they could maintain their conversations about the past events. (2)The frequency of children's looking at their mothers was significantly related to the numbers of the mothers' past discourse.3.Study 2 : This study compared 5 pairs of deaf children (age:2-3 years) and their mothers and 11 pairs of hearing children and their mothers on the past and mental state discourse. Mothers encouraged their children talk about the past events, looking at the photos that showed them. The main findings were as follows. (1)There were variations in deaf children's past and mental state discourse skills, depending on their verbal skills and their mothers' talk styles. (2)Deaf mother used more sign language so effectively that her child talked more past events and her mental states than other hearing children did.